title: Supplemental vitamin D3 and zilpaterol hydrochloride. I. Effect on performance, carcass traits, tenderness, and vitamin D metabolites of feedlot steers.
abstract: Angus × Simmental steers (n = 210; initial BW 314 ± 11 kg) were separated into heavy and light BW blocks and allotted evenly by BW to 6 treatments (3 heavy and 2 light pens per treatment) to determine the effect of supplemental vitamin D3: 0 IU (no D), 250,000 IU for 165 d (long-term D), or 5 × 10(6) IU for 10 d (short-term D) on performance, carcass traits, vitamin D metabolites, and meat tenderness in steers fed either 0 (NZ) or 8.38 mg/kg zilpaterol hydrochloride (ZH) daily for 21 d. Placebo or ZH was added to the diet 24 d, and short-term D was added 13 d before slaughter. Vitamin D3, ZH, and placebo were all removed from the diet 3 d before slaughter. Steers fed ZH tended to have improved overall G:F compared with steers not fed ZH (P < 0.09). Overall performance was not affected by long-term D, with or without ZH (P = 0.11) compared with no D, with or without ZH. Short-term D decreased final BW, ADG, and G:F (P = 0.04) compared with no D, when ZH was not fed. Zilpaterol hydrochloride increased HCW, dressing percentage, and LM area (P < 0.01); and decreased fat thickness, yield grade, and marbling (P < 0.03). Carcass traits were not impacted by long-term D without ZH (P > 0.13), but long-term D with ZH decreased percentage KPH (P < 0.02). Compared with no D, short-term D tended to decrease HCW (P < 0.07), decreased fat thickness (P < 0.01), and tended to increase dressing percentage (P < 0.10) when ZH was not fed, yet did not impact carcass traits when ZH was fed (P < 0.13). Feeding ZH tended to decrease (P < 0.09) LM 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. The long-term D treatment increased LM vitamin D3 and 25-hydroxyvitamin D3 (25OHD3) 18- and 5-fold, respectively, when ZH was not fed (P < 0.04) and increased LM 25OHD3 by 4-fold when ZH was fed (P < 0.01). Short-term D increased LM vitamin D3 and 25OHD3 by 52- and 9-fold, respectively, when ZH was not fed (P < 0.01), and by 24- and 9-fold, respectively, when ZH was fed (P < 0.01). Also, short-term D increased LM 1,25(OH)2D3 by 2-fold (P < 0.04) when ZH was fed. Warner-Bratzler shear force (WBSF) was greater for ZH steaks than non-ZH steaks at 7, 14, and 21 d postmortem aging (P < 0.01). Vitamin D did not reduce WBSF (P = 0.18). When ZH was fed, long-term D tended to increase WBSF in steaks aged 21 d (P = 0.06). In conclusion, ZH improved carcass leanness and decreased tenderness, and vitamin D feeding increased vitamin D3 metabolites in LM, but did not improve tenderness in steers fed ZH.
authors.affiliation: Department of Animal Science, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: K T
authors.initials: KT
authors.lastname: Korn
authors.forename: R P
authors.initials: RP
authors.lastname: Lemenager
authors.forename: M C
authors.initials: MC
authors.lastname: Claeys
authors.forename: M
authors.initials: M
authors.lastname: Engstrom
authors.forename: J P
authors.initials: JP
authors.lastname: Schoonmaker
mesh_terms: D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D001823:Body Composition / Q000187:drug effects*; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D002762:Cholecalciferol / Q000008:administration & dosage / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D007668:Kidney / Q000187:drug effects / Q000502:physiology; D008099:Liver / Q000187:drug effects / Q000502:physiology; D008297:Male; D008460:Meat / Q000032:analysis* / Q000592:standards; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D011897:Random Allocation; D014297:Trimethylsilyl Compounds / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D000318:Adrenergic beta-Agonists; D014297:Trimethylsilyl Compounds; C475840:Zilpaterol; D002762:Cholecalciferol